Visualising The Bowel Flashcards
What are X-rays?
A form of penetrating electromagnetic radiation used to image structures in the body, typically taken posterior-anteriorly, because closer objects will appear more blurry on film. At least 2 projections are required to view the structures clearly.
What are the black images on X-ray?
Air
What appears dark grey on X-ray?
Fat
What appears light grey on X-ray?
Water
What appears off-white on X-ray?
Bone.
What appears stark-white on X-ray?
Metal.
What contrast agent is used in X-rays?
Barium due to being radiopaque in the form of
A meal, via ingestion of a drink containing barium
Enema, which is inserted via the anus to pass through the entire colon.
What is double contrast?
Both a metal agent and air is used to provide contrast.
How does the bowel appear on an X-ray when supine vs erect?
When supine: bowel is higher up, in relation to pelvis.
When erect: bowel is lower down, in relation to pelvis.
Which contrast agent is more typical used in angiograms?
Iodine which is highly radiopaque.
How are CT images produced?
Multiple X-rays are picked up by a detector, which creates a tomogram that creates a numerical value based on the radio density of the image. These radiodensitieis are converted into shades of grey to be picked out by the image.
What does brightness in CT scan without the use of a contrasting agent indicate?
Vessel calcification.
What is a T1-weighted MRI?
Enhances the viewing of fat structures so it is brighter and suppresses water signals so water and inflammation appear darker on images. It has a shorter relaxation time after applying electromagnetic frequency
What is a T2-weighted MRI?
Enhances the viewing of water signals so water and inflammation appear brighter and fat appears darker. T2-weighted MRIs have a longer relaxation time after applying electromagnetic frequency before returning to normal.
What are the types of MRI images?
T2 weighted images vs T1 weighted images
Fat saturated vs Vascular contrast images
-> MRIs are ideal for soft tissue contrast, and tissue with little tendon appear the darkest.
